Color reproduction correction device and correction method for an imaging apparatus

Abstract

A color reproduction correction device for an imaging apparatus that obtains color signals with a plurality of spectral characteristics by imaging an object to be imaged. A color image is obtained by subjecting the color signals to signal processing, wherein the color reproduction correction device includes a light source inferring device which infers the type of illuminating light source being used. A memory device stores, for each of a plurality of predetermined light sources, constants for correction matrix operations which are determined so that the mean values of the absolute values of the distances between values obtained by converting the positions on a uniform color space of each of the plurality of colors of the object illuminated by the respective light sources into the respective corresponding positions on the uniform color space when white light from the reference light source of a display device taking into consideration the adaptive effect of the eyes, and the positions on the uniform color space of colors corresponding to the respective colors of the object being imaged that are obtained when output signals produced by applying the correction matrix operations to the color signals of the imaging device are displayed by the display device, are minimized. The operating device also extracts correction matrix constants corresponding to the illuminating light source inferred by the light source inferring device from the memory device and performs correction matrix operations on the color signals, at the time of imaging.

What is claimed is:  
     
       1. A color reproduction correction device for an imaging apparatus that obtains color signals having a plurality of spectral characteristics by imaging an object, and generates a color image to be displayed by subjecting the color signals to signal processing, the color reproduction correction device comprising: 
       a light illuminating source inferring device for inferring an illuminating light source;  
       memory means that stores, for each of a plurality of illuminating light sources, constants for correction matrix operations; and  
       an operating means that extracts from the memory means the correction matrix constants corresponding to the inferred illuminating light source, at the time of the imaging, and performs correction matrix operations on the color signals to be reproduced,  
       wherein the constants of the correction matrix operations are determined by minimizing a mean value of an absolute value of distances between:  
       (a) corresponding color positions on a uniform color space, obtained by converting positions of each of a plurality of colors of the object illuminated by its respective inferred illuminating light source, into the corresponding positions on the uniform color space for a display device; and  
       (b) corresponding color positions on the uniform color space of color signals corresponding to respective colors of the object obtained when output color signals are produced by applying correction matrix operations to the color signals of the imaging apparatus illuminating light source, and are displayed by the display device, and  
       wherein a reference white color of the display device is different than a reference white color of the illuminating light source.  
     
     
       2. The color reproduction correction device for an imaging apparatus according to  claim 1 , wherein the light illuminating source inferring device infers the type of the illuminating light source based on white balance control signals used for white balance processing of the plurality of color signals. 
     
     
       3. The color reproduction correction device for an imaging apparatus according to  claim 2 , wherein the the correction matrix operations, for each of the plurality of color signals following the correction operation, is expressed as the sum of: 
       a) one color signal of the plurality of color signals; and  
       b) values obtained by multiplying each of a plurality of difference signals between the plurality of color signals by a constant.  
     
     
       4. The color reproduction correction device for an imaging apparatus according to  claim 3 , wherein the operating means performs correction matrix operations on a plurality of color signals by performing white balance processing on the plurality of color signals. 
     
     
       5. The color reproduction correction device for an imaging apparatus according to  claim 2 , wherein the correction matrix operations, for each of the plurality of color signals following the correction operation, is expressed as the sum of: 
       a) one color signal of the plurality of color signals; and  
       b) values obtained by multiplying each of a plurality of difference signals between the plurality of color signals by a constant.  
     
     
       6. The color reproduction correction device for an imaging apparatus according to  claim 5 , wherein the operating means performs correction matrix operations on a plurality of color signals by performing white balance processing on the plurality of color signals. 
     
     
       7. The color reproduction correction device for an imaging apparatus according to  claim 1 , wherein the operating means performs correction matrix operations on a plurality of color signals by performing white balance processing on the plurality of color signals. 
     
     
       8. A color reproduction correction device for an imaging apparatus that obtains color signals having a plurality of spectral characteristics by imaging an object, and generates a color image to be displayed by subjecting the color signals to signal processing, the color reproduction correction device comprising: 
       a light illuminating source inferring device for inferring an illuminating light source;  
       memory means that stores, for each of a plurality of illuminating light sources, constants for correction matrix operations;  
       a constant inferring means which infers correction matrix constants that approximates most closely the illuminating light source inferred by the light illuminating source inferring device, based on the constants stored in the memory means at the time of imaging; and  
       an operating means which perform correction matrix operations on the color signals based on the correction matrix constants output by the constant inferring means,  
       wherein the constants of the correction matrix operations are determined by minimizing a mean value of an absolute value of distances between:  
       (a) corresponding color positions on a uniform color space, obtained by converting positions of each of a plurality of colors of the object illuminated by its respective inferred illuminating light source, into the corresponding positions on the uniform color space for a display device; and  
       (b) corresponding color positions on the uniform color space of color signals corresponding to respective colors of the object obtained when output color signals are produced by applying correction matrix operations to the color signals of the imaging apparatus illuminating light source, and are displayed by the display device;  
       wherein a reference white color of the display device is different than a reference white color of the illuminating light source.  
     
     
       9. The color reproduction correction device for an imaging apparatus according to  claim 8 , wherein the color signals with a plurality of spectral characteristics are selected so that any variation in the correction matrix constants applied to difference signals between the plurality of color signals in the correction matrix of the respective color signals is minimized. 
     
     
       10. The color reproduction correction device for an imaging apparatus according to  claim 9 , wherein the correction matrix operations, for each of the plurality of color signals following the correction operation, is expressed as the sum of: 
       a) one color signal of the plurality of color signals; and  
       b) values obtained by multiplying each of a plurality of difference signals between the plurality of color signals by a constant.  
     
     
       11. The color reproduction correction device for an imaging apparatus according to  claim 10 , wherein the light illuminating source inferring device infers the type of the illuminating light source based on the white balance control signals used for white balance processing of the plurality of color signals. 
     
     
       12. The color reproduction correction device for an imaging apparatus according to  claim 9 , wherein the operating means performs correction matrix operations on a plurality of color signals by performing white balance processing on the plurality of color signals. 
     
     
       13. The color reproduction correction device for an imaging apparatus according to  claim 8 , wherein the correction matrix operations, for each of the plurality of color signals following the correction operation, is expressed as the sum of: 
       a) one color signal of the plurality of color signals; and  
       b) values obtained by multiplying each of a plurality of difference signals between the plurality of color signals by a constant.  
     
     
       14. The color reproduction correction device for an imaging apparatus according to  claim 13 , wherein the light illuminating source inferring device infers the type of the illuminating light source based on white balance control signals used for white balance processing of the plurality of color signals. 
     
     
       15. The color reproduction correction device for an imaging apparatus according to  claim 14 , wherein the operating means performs correction matrix operations on a plurality of color signals by performing white balance processing on the plurality of color signals. 
     
     
       16. The color reproduction correction device for an imaging apparatus according to  claim 13 , wherein the operating means performs correction matrix operations on a plurality of color signals by performing white balance processing on the plurality of color signals. 
     
     
       17. The color reproduction correction device for an imaging apparatus according to  claim 8 , wherein the light illuminating source inferring device infers the type of the illuminating light source based on white balance control signals used for white balance processing of the plurality of color signals. 
     
     
       18. The color reproduction correction device for an imaging apparatus according to  claim 17 , wherein the operating means performs correction matrix operations on a plurality of color signals by performing white balance processing on the plurality of color signals. 
     
     
       19. The color reproduction correction device for an imaging apparatus according to  claim 8 , wherein the operating means performs correction matrix operations on a plurality of color signals by performing white balance processing on the plurality of color signals. 
     
     
       20. A color reproduction correction method for an imaging apparatus that obtains color signals having a plurality of spectral characteristics by imaging an object, and generates a color image to be displayed by subjecting the color signals to signal processing, the color reproduction correction method comprising the steps of: 
       inferring a light illuminating source;  
       storing for each of a plurality of illuminating light sources, constants for correction matrix operations in a memory means; and  
       extracting from the memory means the correction matrix constants corresponding to the inferred illuminating light source, at the time of the imaging, and performs correction matrix operations on the color signals to be reproduced,  
       wherein the constants of the correction matrix operations are determined by minimizing a mean value of an absolute value of distances between:  
       (a) corresponding color positions on a uniform color space, obtained by converting positions of each of a plurality of colors of the object illuminated by its respective inferred illuminating light source, into the corresponding positions on the uniform color space for a display device; and  
       (b) corresponding color positions on the uniform color space of color signals corresponding to respective colors of the object obtained when output color signals are produced by applying correction matrix operations to the color signals of the imaging apparatus illuminating light source, and are displayed by the display device;  
       wherein a reference white color of the display device is different than a reference white color of the illuminating light source.  
     
     
       21. The color reproduction correction method for an imaging apparatus according to  claim 20 , wherein the light illuminating source inferring device infers the type of the illuminating light source based on white balance control signals used for white balance processing of the plurality of color signals. 
     
     
       22. The color reproduction correction method for an imaging apparatus according to  claim 20 , wherein the correction matrix operations, for each of the plurality of color signals following the correction operation, is expressed as the sum of: 
       a) one color signal of the plurality of color signals; and  
       b) values obtained by multiplying each of a plurality of difference signals between the plurality of color signals by a constant.  
     
     
       23. The color reproduction correction method for an imaging apparatus according to  claim 20 , wherein the operating means performs correction matrix operations on a plurality of color signals by performing white balance processing on the plurality of color signals. 
     
     
       24. A color reproduction correction method for an imaging apparatus that obtains color signals having a plurality of spectral characteristics by imaging an object, and generates a color image to be displayed by subjecting the color signals to signal processing, the color reproduction correction method comprising the steps of: 
       inferring a light illuminating source;  
       storing for each of a plurality of illuminating light sources, constants for correction matrix operations in a memory means;  
       inferring correction matrix constants that approximate most closely the illuminating light source inferred by the light illuminating source inferring device, based on the constants stored in the memory means at the time of imaging; and  
       performing correction matrix operations on the color signals based on the correction matrix constants output by the constant inferring means,  
       wherein the constants of the correction matrix operations are determined by calculating a mean value of an absolute value of a distance between corresponding color positions on a uniform color space, obtained by converting positions of each of a plurality of colors of the object imaged, illuminated by its respective inferred illuminating light source, into the corresponding positions on the uniform color space for a display device, and  
       wherein a reference white light of the display device is different than a reference white light of the illuminating light source and the positions of color signals corresponding to respective colors of the object imaged on the uniform color space that are obtained when output color signals produced by applying correction matrix operations to the color signals of the imaging apparatus displayed by the display device, are minimized.  
     
     
       25. The color reproduction correction method for an imaging apparatus according to  claim 24 , wherein the color signals with a plurality of spectral characteristics are selected so that any variation in the correction matrix constants applied to difference signals between the plurality of color signals in the correction matrix of the respective color signals is minimized. 
     
     
       26. The color reproduction correction method for an imaging apparatus according to  claim 24 , wherein the correction matrix operations, for each of the plurality of color signals following the correction operation, is expressed as the sum of: 
       a) one color signal of the plurality of color signals; and  
       b) values obtained by multiplying each of a plurality of difference signals between the plurality of color signals by a constant.  
     
     
       27. The color reproduction correction method for an imaging apparatus according to  claim 24 , wherein the light illuminating source inferring device infers the type of the illuminating light source based on white balance control signals used for white balance processing of the plurality of color signals. 
     
     
       28. The color reproduction correction method for an imaging apparatus according to  claim 24 , wherein the operating means performs correction matrix operations on a plurality of color signals by performing white balance processing on the plurality of color signals.